The telephone system of the British post office. A practical handbook (1901)
Herbert, Thomas Ernest · London, New York, Whittaker and Co. · leaf 101
upon the handle whendepressed completes the primary circuit. This enables the operator tolisten to a conversation without introducing the noise from the switchroom upon the wire. At the larger exchanges the transmitter and receiver are designed forattachment to the person of the operator in order… … ■rMfiite.ce . CA»B0I1 BLOCK IHTeKSTICES viTH FLyinnE. I. Figure 74. pad attached, which rests above the operators right ear. The connectionis effected by means of a two-conductor flexible cord which terminates ina red-covered peg. The general appearance of the apparatus is shown inFigure 73, but it…
Telephone · Postal service
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